Howdy! I have a 1989 2 Door Laredo 4.0. It recently started making a popping noise near the exhaust manifold. So I replaced the gaskets, it still made the noise, so I went thicker and replaced it again, it still made the noise, so I replaced it with an entirely new manifold, the thickest gasket, new donut, new motor mounts, and new bolts. It is STILL blowing out the gasket right around the middle two exhaust ports. I then disconnected the Cat to check if it was clogged and causing a backfire into the manifold and it appeared to be clear and the manifold was still leaking even with the Cat disconnected. I have not check to see if the head is warped yet, but I figured that the last gasket would have accounted for that, considering that it was very thick. Anyone else of anything similar to this?

 

Two things to check, is the manifold sealing surface flat? Is the manifold cracked?

 

thanks for the reply,

Manifold is not cracked (the old one or the new one) the sealing surface "looks" flat, I did not take a straight edge to the head was it was off to double check. But I did clean it with a razor blade and nothing seemed out of shape.

 

Are you for sure on the locating pins during assembly? Classic error

 

Pretty sure, I am goin to disassemble and try again. Last time I had it completely out and I was going stupid slow, so I'm pretty sure everything mated in the correct position but at this point who the hell knows.

 

Hi, not sure if the really old models have the same exhaust mounting systems as my 92/96/98/01. The bottom front and back bolt on the exhaust manifold is a fairly large stud that you put a nut over when assembling. Its fairly hard to screw that up...But the intake portion has just 2 small alignment pins that are fairly easy to misalign or not seat properly. Also the intake /exhaust mounting bolts are a nightmare to get to...especially the middle lower 3 or 4 since they are completely blind and you cant really get a finger in there. You might have missed or not properly tightened those middle lower ones. There are 11 total including the stud nuts.. You did use the large thick cone shaped washers, correct?

 

Sure am, on my 89 the two mounting points are double threaded with a bolt. I replaced all the other bolts with brand new grade 8 bolts and made sure they all had their cone washers, I even took a thread cleaner to each hole to make sure each one had the same depth and to clean anything that may be leftover inside there. Everything seemed to be on the up and up.

 

I found this on other threads, I did a kind of star pattern when I put these on, I did not do this. It is the area near the Number 1 bolt that appears to be blowing out when mounted...

 

photo doesn't seem to be coming through

 

Here is the photo

 

That picture is mine and it shows that the lower front and back " bolts "..are smaller dia permanently mounted studs. The nbr 1 bolt is tough to get on. You may have to do this the hard way and remove the intake by taking all the bolts out except the studs...they only hold the exhaust. Then reinstalling the bolts into the exhaust only and see if the manifold sits flush on the block Also you must install all the bolts finger tight to 1 or 2 foot pounds first ...then torque to the proper tightness in the correct sequence